Technology which gives concrete high fluidity and high filling ability to make it possible to prepare concrete without compacting operations has been developed as the so-called "high performance concrete" of Professor Okamura of the Department of Engineering of Tokyo University (see, Doboku Seko, October 1989 and JP-A 3-237049). Further, concrete containing a non-segregation admixture used for in-water segregation concrete has also been developed.
In the case of high performance concrete, however, it necessary to carefully select the materials in order to produce concrete which has a very high powder content. Moreover, small amounts of viscosity enhancers must be used in order to prevent segregation of the concrete while it is in the fluid state. Therefore very careful quality control must be exercised over the materials being used, and strict production control is also required. It is quite difficult to perform on-site formulation and utilization of this type of concrete.
Further, concrete containing an in-water non-segregation admixture has poor fluidity, so when it is poured into highly reinforced forms, it is very difficult to achieve proper filling without compaction. Also, because it has a large unit water content, this concrete has a high degree of shrinkage during drying, and which, due to the large air bubbles within, causes lowered resistance to freezing and thawing and thus, lowered durability.
Thus, the above prior art is problematic. That is, the preparation of the concrete is readily affected by conditions for the preparation, and the allowable variation of the water content in the concrete and the allowable temperature variation in summer and winter are small.